Method of forming propeller tip sections



March 29, 1949. E. R. KOPPEL 2,465,884

ETBOD 0F FORIING PROPELLER TIP SECTIONS Filed Jan. 22, 1944 SAW 3.

AT TORNE! mm mm am a. m 5

Patented Mar. 29, um

Ernst It. Koppel. Milwaukee, Wis., assignor to Corporation, Milwaukee, Win, a.

corporation of NewYork Application January 22, 1944, Serial No. 519,885

This invention relates to a method of forming propeller tip sections.

Heretoiore it has been the practice to employ expensive alloy seamless cylindrical blanks and to taper machine the same on the inside to provide a progressive varying in wall thickness from end to end, followed by an electroiorming operation which provides a conical blank of substantially uniform wall thickness from which the tip is made. Considerable metal had to be machined away, and in making a complete and finished tip section for a propeller it was ordinarily necessary to start with a blank weighing about six times the weight or the finished section. The difference in weight was scrap.

The object of the present invention is to reduce the scrap involved in makingsuch a tip and to reduce the labor and machining operations so that a less costly tip section can be fabricated.

In carrying out the invention a taper rolled plate varying in thickness from end to end is formed into tubular shape and its longitudinal side edges welded together to provide the blank which is then conically shaped and subsequently flattened into the tip section.

The invention enables the employment oi a blank weighing less than three times the weight of the finished tip section, and thereby reduces the amount of scrap metal by about two-thirds.

The accompanying drawing illustrates the practice of the invention, and the views therein are as follows:

Figure 1 is a perspective view of the fiat blank from which two tips are made;

Fig. 2 is an edge elevation of the blank after taper rolling and showing severing oi the same into two halves with each half tapering in thickness from end to end and having one end thicker than the other;

Fig. 3 is a View similar to Fig. 2 showing a modified type of taper rollin Fig. 4 is a perspective view of a single tip section blank aiter forming to tubular shape and welding along a longitudinal seam, with parts broken away and sectioned; Y

Fig. 5 is a longitudinal axial section through the tubular blank after a plain carbon steel sh'ank has been welded thereto; which in this embodiment is utilized for chucking purposes;

' Fig. 6 is a schematic showing or the electroforming operation in which the blank is formed to a substantially conical shape;

Fig. 'I is a perspective view of the blank after extrusion of the side fins thereon and removal of the shank;

1 Gaim. (Cl. 29-1583) 2 Fig. 8 is a perspective view of the blank after fiattening to blade shape;

Fig. 9 is a view similar to Fig. 4 showing a double blank, made from a fiat blank as shown in Fig. 3; and

Fig. 10 is a similar view of the blank after electroiorming thereof.

An ordinary sheet metal blank or rectangular or square shape and of high strength low alloy steel is first taper rolled longitudinally to vary the thickness thereof.

The sheet i is preferably of a length suitable for the making of two tips, and the taper rolling may produce a sheet that is thinnest in the middle and of gradually increasing thickness toward the end edges, as shown in Fig. 2, or it may produce a blank that is thickest in the middle and of gradually decreasing thickness toward the ends, as shown in Fig. 3.

After taper rolling as shown in either Fig. 2 or Fig. 3, the sheet is trimmed and then severed transversely in the middle to produce-two blade blanks. These are then formed into tubular shape with their longitudinal meeting edges electrically as flash welded together as illustrated in Fig. 4. I!

desired, two such rolled sheets or less width may be formed into complementary semi-tubular sections and their corresponding meeting edges welded together to provide the tubular blank. It

is also possible to form the'blanks of Figs. 2 and 3 into tubular shape and weld the same, as shown in Fig. 9, and to thereafter sever the same into individual blade blanks as shown in Fig. 4.

A tubular shank 2 of ordinary steel is then electrically flash welded to the thicker end of the blank to enable chucking ior electroforming.

In electroforming the thinner end of the blank is forced into a conical die cavity formed between two or more spaced die electrodes 3 which supply heating current to the blank from a source 4 of electricity. The blank ismounted in a chuck 5 on \,a slide 6, and the chuck and blank are rotated by a suitable motor I on the slide, as the slide advances toward-the die. a

After the blank is conically formed, it is upset, preferably in the same dies, to extrude a pair of side fins 8 on opposite sideso! the blank as shown in Fig. I. The fins 8 constitute the leading and trailing edgesof the tip section. The blank is g. subjected to suitable machining and coining operations, the shank I removed and then the blank is flattened to blade shape with the pitch twist therein as shown in Fig. 8.

The rolled sheet of either Fig. 2 or Fig. 3 may llbe formed and welded into a tube as illustrated bethe being electroformed.

eases in Fig. 9, providing two blade blanks which may reaiter severed to provide two blanks such as the blank Fig. 4.

ltdesiredtheuseoi'ashankmaybeeliminated by conically forming the two blade blanks prior to severing. Instead oi employing a shank, one end serves for chucking while the other is Then the formed end serves for chucking while the first is being formed, producing a blank that is conically reduced at both ends, as shown in Fig. 10. The fins are extruded and the blank is severed transversely in the middle to produce two tip section blanks which are then flattened as described previously.

The invention in this latter phase saves the labor and material involved in the applying and removal of the shank 2.

The invention may have various embodiments within the scope of the accompanying claim.

I claim:

In the manufacture of propeller tip sections,

the steps of taper rolling a flat sheet metal blank 01' double thelength required for one section to provide a sheet which is thickest in the middle and which tapers to a thinner thickness at the opposite ends to embody two blade blanks, forming the sheet into a tube and welding the longitudinal edges thereof, forming one end of the tube in a machine to a conical shape with the end trimmed, machined and y in the middle to provide two tip secthroughout. and

end.

ERNST R. KOPPEL.

REFERENCES CITED The following references are of record in the tile 0! this patent:

UNITED STATES PATENTS Number 3 Number Name Date Gracey Oct. 11. 1887 Murray May 11, 1920 Dun Feb. 23, 1926 Wishon Mar. 23, 1926 Jamison Apr. 19, 1932 Squires Jan. 2, 1934 Squires Nov. 13, 1934 Jamison Dec. 4, 1934 Squires Nov. 29, 1938 Sinclair Mar. 21, 1939 FOREIGN PATENTS Country Date Great Britain June 12, 1923 Great Britain Juhr 5, 1943 

